Field of the Invention
Embodiments of the present invention relate to apparatuses, methods, devices, and systems for use in the treatment of wounds by topical negative pressure (TNP) therapy.
In recent years TNP therapy has become increasingly important in the field of improved treatment of wounds by making the healing thereof faster and more controlled.
The basic principle of TNP therapy is to create a closed cavity over the wound itself by means of a thin, flexible sealing film adhered to the patient's sound skin surrounding the wound; admitting one end of an aspirant conduit into the closed cavity, the conduit being sealed to the flexible film, for example; and connecting a distal end of the aspirant conduit to a vacuum source such as an electrically driven vacuum pump, for example, to create a pressure lower than the surrounding ambient atmospheric pressure within the wound cavity. As is known to the skilled person the lower pressure creates many beneficial therapeutic effects on the wound including increased blood flow to the wound and faster granulation of tissue, for example. There are very many variations on this basic principle of TNP therapy.
The types of wounds treated by TNP therapy generally range from quite small at about 5 cm2 to very large traumatic wounds and burns of no particular maximum dimension. Such wounds may also have significant depth and therefore, significant volume. It is necessary to control the way in which a wound heals. For example, the wound should heal from the base up and close in from the edges desirably in a uniform manner. In particular it is desirable that the wound does not close over and form an occluded cavity in the flesh which is extremely undesirable from the patient's point of view as such form sites for infection.
To prevent the formation of occluded cavities during TNP therapy, the wound is usually packed with a filler which desirably has some resilience or “bounce” to resist the compressive forces created during TNP therapy by outside ambient atmospheric pressure bearing down on the wound due to the vacuum created in the wound cavity. The purpose of the filler is to keep the surrounding edges of the wound apart so that they cannot grow over and form a cavity. The filler may also perform the function of providing fluid flow channels between the wound and the filler in order to provide a uniform reduced pressure distribution over the surface area of the wound and to promote efficient aspiration of exudate fluids away from the wound surface and generally into a remote waste receptacle associated with the aspirant conduit.
As noted above there are very many variations on the basic TNP therapy principle and to illustrate how complex TNP therapy may be reference is made to the documents described below and which are of common ownership herewith.
TNP therapy often involves the provision within a dressing to which a negative or a positive pressure is applied a bag member (sometimes also referred to as a bladder) which may be used to at least partially fill a volume of a wound, for example. Furthermore, fluctuating pressure or pressure cycling may be applied to the bag member in order to work the tissue in and around the wound region for therapeutic reasons, for example.
There are many commercially available bag members which may be included in a wound dressing, however, commercially available bag members suffer from the disadvantage that they are obviously of predetermined size and shape, for example, and there may not be available a bag member of a corresponding form to that of the wound which needs treatment. Such unavailability may not be just the unavailability in the particular hospital formulary or store, for example, but a suitably sized and shaped bag member may not be available at all commercially.
Description of the Related Art
In International patent application, WO 2004/037334, apparatus, a wound dressing and a method for aspirating, irrigating and cleansing wounds are described. In very general terms, this application describes the treatment of a wound by the application of topical negative pressure (TNP) therapy for aspirating the wound together with the further provision of additional fluid for irrigating and/or cleansing the wound, which fluid, comprising both wound exudates and irrigation fluid, is then drawn off by the aspiration means and circulated through means for separating the beneficial materials therein from deleterious materials. The materials which are beneficial to wound healing are recirculated through the wound dressing and those materials deleterious to wound healing are discarded to a waste collection bag or vessel.
In International patent application, WO 2005/04670, apparatus, a wound dressing and a method for cleansing a wound using aspiration, irrigation and cleansing wounds are described. Again, in very general terms, this application utilises a similar apparatus to that in WO 2004/037334 with regard to the aspiration, irrigation and cleansing of the wound, however, it further includes the important additional step of providing heating means to control the temperature of that beneficial material being returned to the wound site/dressing so that it is at an optimum temperature, for example, to have the most efficacious therapeutic effect on the wound.
In International patent application, WO 2005/105180, apparatus and a method for the aspiration, irrigation and/or cleansing of wounds are described. Again, in very general terms, this document describes similar apparatus to the two previously mentioned documents hereinabove but with the additional step of providing means for the supply and application of physiologically active agents to the wound site/dressing to promote wound healing.
The contents of the above references are hereby incorporated by reference in their entireties.
In spite of the self-evident growing complexity of TNP therapy, in general the field of wound fillers, which are a vital element in the therapy, has changed or improved very little over the years that TNP therapy has been developing. Aside from complicated and expensive inflatable bags, most of the fillers in use are based either on foam or on cotton gauze. Foam fillers are usually cut with scissors to the required shape (of the wound) by a clinician. However both foams and gauzes have the disadvantage that the cell or pore size is often too large and often results in growing tissue growing into the cells and adhering the foam to the wound causing further damage and trauma to the wound and patient on removal. When gauze is used as a filler, however, clinicians are instructed to “fluff up” the gauze to increase its volume which can cause problems in that the actual form of the gauze as packed into wounds is very variable. A further disadvantage with both foams and gauze when cut to fit wounds is that of debris. Gauze and foam are particularly prone to shedding fibres and particles when cut and these inevitably find their way into the wound and become occluded therein which can lead to later infection.
Foam or gauze as the wound filling medium has the additional disadvantage of tissue ingrowth into the pores of the filler and which may cause damage to newly formed granulation tissue on removal and also pain to the patient. Furthermore, such porous materials are subject to becoming saturated with wound exudate fluids causing a build up of bacteria leading to infection.
All of the wounds to which the above documents are addressed may require the provision of a bag member or bladder within a wound dressing and those currently available may be unsuitable. Indeed, International patent application WO 2004/037334 referred to above shows at FIGS. 13A and 20 embodiments employing pre-formed inflatable bladders used in apparatus for wound therapy.
Other reasons why inflatable bladder-type wound fillers may be used is to apply an uneven or textured or otherwise non-smooth surface possessed by the bladder surface directly onto a wound surface/interface. The textured surface assists in “working” the wound surface thereby enhancing the therapeutic effect of pressure cycling. A textured surface also provides a plurality of fluid flow channels at the interface between the wound filler and the wound surface to assist in a more even (negative) pressure distribution over the wound surface and a more rapid and even drainage of fluids such as wound exudates, for example, away from the wound region towards an aspiration conduit generally forming part of a TNP therapy apparatus.
Examples of known inflatable wound fillers are described in WO-A-2005/082435 and GB-A-2378392, the entireties of both of which are hereby incorporated by reference.
In WO-A-2005/082435, an inflatable bag or bladder-type wound filling member is used to fill the wound cavity. The bladder member is described as having two layers, however, the two layers appear to be in the form of an integral structure. A problem with this type of structure is that it is difficult and costly to manufacture. The structure also makes the bladder relatively rigid and stiff and inflexible against a wound surface possibly leading to discomfort and trauma.
GB-A-2378392 describes a wound irrigation and/or suction device comprising an inflatable bladder or pouch having a plurality of flexible conduits provided within and running through the bladder interior, the conduits having outlet/inlet apertures on the bladder surface. The conduits are fluid transfer conduits to either supply fluid to the wound or to conduct fluid away from the wound or both. However, a problem with this particular construction is that it is extremely complex and costly to manufacture.
It is an object of certain embodiments described herein to overcome or mitigate some of the disadvantages of known wound fillers.
It is further intended in certain embodiments to provide a method of making a suitably sized and shaped bag member in a dressing for a particular wound from materials commonly available in most hospital formularies or stores.